Apparatus for controlling pressure bands



- April 13, 19489 G. D. MARcY 2,=%-;:i9,7?9

APPARATUS FOR CONTROLLING PRESSUREBANDS Filed March 29, 1945 2Sheets$heet l April 13, 33948, MARCY 2,439,779

APPARATUS FOR CONTROLLING PRESSURE BANDS Filed March 29, 1945 2Sheets-Sheet 2 Patented Apr. 13,1948

APPARATUS FOR CONTROLLING PRESSURE ANDS Grosvenor D. Marcy, NewtonHighlands, Mass,

assignor to Boston Woven Hose & Rubber Company, Cambridge, Mass, acorporation of Massachusetts Application March 29, 1945, Serial No.585,468

Claims.

In a vulcanizing machine of the Rotocure type which employs a highlytensioned pressure band in'cooperation with a heated drum, difficultyhas been encountered under some circumstances in maintaining truerunning of the pressure band in the machine. Great annoyance and loss oftime has been caused by the tendency of the pressure band to drift orwork slowly toward one edge or other of the drum as the drum continuesto rotatehour after hour in the vulcanizing operation. Various attemptshave been made to confine the pressure band forcibly to the true andproper path but these have been found objectionable in that they tend todeform the band itself and to create excessive and undesirable friction.In many cases it has become necessary to stop the machine, relieve theband from tension and pressure and shift it back to a central position.This is not only wasteful in time but requires the services of skilledmechanics who can ill be spared, and unless great care is taken theproduct may be damaged by the interruption of the vulcanizing process.The primary object of the present invention is to provide for theaccurate control of the path of movement of the pressure band invulcanizing machines of the type discussed.

The pressure band is of considerable width and operates underexceedingly high tension. I have discovered that occasionally one sideof the band becomes slightly elongated relative to the other side andthat this differential causes lateral creep or drift in the band. I havefurthermore discovered that this difliculty can be cured and the bandcaused to travel in its true and fixed path by placing opposite sides ofthe band under respective tensions proportioned relative to andcompensating for the said diiferential. Under normal conditions oftension the band will tend to creep toward its shorter side and, inaccordance with the invention, I place this side of the band under arelatively greater tension so proportioned as to correct the drift andcause the band to follow a true and fixed path.

The pressure band is tensioned on and extends about an arcuate portionof a vulcanizing drum and about a cylindrical tensioning roll. The bandmay be tensioned by hydraulic pressure acting against the journals ofthe tensioning roll and, as illustrated in Patent 2,039,271, April 28,1936, Bierer, equal pressures have heretofore been exerted on both thesejournals. It appears, however, that such continuous application of equalpressures on both journals causes a condition of unstable equilibrium inthe organization of the machine. The band may depart from an exactlycentered position for various reasons and in such case the operation ofthe equal pressures on the two journals produces a resultant couple thateffects an angular displacement of the tension roll and an unbalancedband tension. This I have found can be corrected only by providingunequal pressures on the tension roll journals so properly proportionedas to provide a balanced tension in the band. The uneven distribution ofstress caused by equal pressures on the journals produces more stretchat one edge of the band than at the other, and this, in turn, permitsmore angular displacement of the tension roll which induces still morelateral drift of the band. Such action forms a pernicious cycle ofmutually aggravating effects which not only causes interruptions inproduction of the product but may progress to the point where one edgeof the band is, stretched beyond its elastic limit and becomespermanently deformed and useless and thereby results in a further andconsiderable financial loss.

Possible causes of an initial lateral displacement of the band from atruly centered position are numerous and cannot be wholly eliminated.

The band itself, due to its size and method of manufacture, may beinitially shorter on one edge than the other or unrelieved internalstresses may be present to cause'unequal elongation under load. Unevenwear of journals may permit slight misalignment of thedrum and rollsaround which the band passes or the uncured stock fed into the press mayvary in thickness, thus causing uneven loading of the band. My inventionrecognizes the presence of such unavoidable factors tending to causelateral movement of the band and provides means for counteracting themand preventing their building up to a point where stopping of themachine or injury to the band and product results.

A further advantage resulting from the invention resides in the factthat bands used on vulcanizing machines equipped with this inventiontend to improve with continued use, rather than to deteriorate. This isdue to the fact that use of my invention continually stretches the shortedge of the band, and over a period of time tends to equalize anyvariation in its effective length, whereas on machines not so equipped,the longer edge of the band is subjected to greater stress than theshorter edge, as explained above, so that its condition becomesprogressively worse, and has resulted in bands having to be discardedbecause they had become deformed beyond the point of usefulness.

As illustrated herein the invention contemplates the employment of meansfor applying controlled and unequal pressures to the journals of thetension roll with the result that the roll is canted in the bandtensioning direction and at an angle placing a relatively greatertension on the shorter side of the band. Such action not onlycompensates for any tendency of the band to run off sidewise butfurthermore tends also to improve the condition of the band and to bringall elements of the machine into stable equilibrium. In other words, ittends to stretch the shorter edge: of the band and so equalize it as awhole. Preferably and as herein shown, this may be accomplished byproviding separate hydraulic connections to cylinders acting on thejournals of the tension roll and providing valve connections and gaugeswhereby the two journals may be subjected to predetermined and unequalpressures.

Another feature of my invention consists in providing indicatingmechanism for the bearings of the journals of the. tension roll to showany angular displacement of the, roll and inform the operator as to thenature of the required adjustmen-t, and in providing pressurecontrolling means conveniently located at one side of the machineandfrom which means the-pressures on the two journals can be -adjusted toand maintained in the required proportions.

The invention herein disclosed and claimed contemplates novel apparatusfor controlling the path of movement of anendless vulcanizing pressureband of the nature described, correcting lateral drift in such a bandand eliminating the faults and disastrous results which would otherwiseoccurandcause costly delays and considerable damage to both machine andproduct.

These and other features of the invention will be best understood andappreciated from the following description of a preferred embodimentthereof selected" for purposes of illustration and shown in theaccompanying drawings in which Fig. 1 is a side elevation of avulcanizing machine embodying my invention,

Fig. 2 is a fragmentary plan view, and

Fig. 3 is a fragmentary perspective view of the pressure bandtensioningmechanism and indicating mechanism.

The rotary vulcanizing machine illustrated in the drawings comprisesaheavy frame embodying spaced side members; In of similar shape rigidlyconnected together and supported on a concrete foundation. Rotatablysupported. in the frame are three cylindrical rolls [2, I3 and i4 overwhich passes an endless pressure band E5 in a general triangular pathwith a. reentrant loop extending from the rolls i2 and I 3 about asubstantial arcuate portion of a large vulcanizing drum It alsorotatably supported by the frame within the general outline of. the pathof the band. The drum isrotated in the direction of the arrow and stripmaterial It to be vulcanized is passed about the drum beneath thepressure band and is vulcanized by steam heat conducted into the drumthrough piping 20. The roll M is a tensioning roll for holding the bandunder pressure on the drum.

Opposite ends of the tensioning roll M are supported in bearings orjournals 2'2 slidably mounted in guideways 24' on the." frame, andcooperating with the journals are hydraulically operated pistons 26moving within cylinders 28 fixed .4 to the frame. Hydraulic pressure issupplied to the two cylinders from a compressor 30 operated by a motor32 through worm and worm wheel gearing 34. A pipe 36 extends from thecompressor to the adjacent cylinder 28 and is provided with acontrolling valve 49 and pressure gauge 42. A branch pipe 44 extends tothe other cylinder and is provided with a controlling valve 4'6 and apressure gauge 48. Oil is conducted from a reservoir 50 to thecompressor through a pipe 52 and, in the case Of excessive pressure, isre turned to the reservoir through a relief valve 54 and pipe 56.

The control valves and pressure gauges are all located at the same sideof the machine within easy reach of the operator and it will be apparentthat he can by closing either valve and manipulating the other valveplace any desired hydraulic pressure within the other cylinder. Suchpressure operates directly against its piston to force its journal andthe corresponding end of the tension roll away from the vulcanizingdrum; When the desired pressure has been attainedv the valve is closedand retains the indicated pressure with; in the cylinder. The othervalve can then be manipulated in like manner to provide the desiredindicated pressure within its cylinder.

As heretofore discussed, various factors. may so affect the operation ofthe pressure bandas to require correction in the operation of the bandas afforded by my invention; These factors include variations in theeifective length of the band across its width, lack of parallelism inthedrum and roll axes, variations in the thickness of the material beingvulcanized, etc, any of which may require compensating adjustment if theband is to continue to run in a substantially centered path. If allfactors were perfect and correct, the axis of the tension roll I4 shouldbe parallel with. that of the drum and other rolls and the pressure onthe two pistons 26. should be equal, and under such conditions. the bandwould run in a truly centered path. It will be understood however thatin practice this perfect condition never exists.

The invention contemplates adjustments which will make corrections forfaults inherent in. the construction of the pressure band. and resultingfrom dimensional errors, uneven shrinkage after welding 01' unrelievedinternal-stresses, whereby the band is caused to travel. unevenly asabove described. Furthermore, the invention eonteme plates not only thecorrecting of the travel; path of movement of the band but embodiesatreatment of progressive and. controlled stretching. of tight portionsthereof over a period of time until substantial uniformity is produced.The pressure band is usually of sheet steel and ordinarily constructedin the manner described in. Patent 2,083,527, June 8, 1937, Bierer, butmay be fabricated upon a woven wire base.

It will be apparent that varying of the pres sures on the pistons 26causes the tension roll to be canted from a position. departing: fromits parallel relation with the vulcanizing drum. It is important thatthis parallel relationship and the departure therefrom be under definiteobservation and control, and means is provided herein to indicate thiscondition to the operator at all times. A gauge or indicator 5!} isamned to the journal 22 at the control side of the ma. chine and in viewof the operator. It. has-awire 52 extending therefrom about sheaves 53,5t and 55 to a hook 66- attached-to the other journal. This auge soadjusted that its index pointsto '5 zero when the two journals are inparallelism with the axis of the vulcanizing drum. It will be apparentthat moving both journals as a unit will have no effect on the gauge butthat movin either journal along its guideway 25 relative to the otherwill move the index and indicate the departure of the tensioning rollfrom such parallelism in either direction relative to the vulcanizingdrum and other rolls.

Having thus disclosed my invention and described in detail anillustrative embodiment thereof, I claim as new and desire to secure byLetters Patent:

1. In a vulcaniz-ing machine of the continuous type employing a drum anda cooperating endless pressure band; a band-tensioning roll havingbearings at its opposite ends independently movable lengthwise of theband, in combination With a gauge mounted on one of said bearings andmeans cooperating with the gauge and the other bearing for indicating onthe gauge displacement or" said bearings with respect to each other.

2. In a vulcanizing machine of the continuous type employing a drum anda cooperating endless pressure band; a band-tensioning roll havingindependently movable bearings at its opposite ends, in combination withmeans including a single gauge located at one side of the machine and aconnecting element attached to and cooperating with the gauge and saidbearings for indicating on the gauge the relative displacement of thebearings from normal position.

3. In a vulcanizing machine of the continuous type employing acylindrical vulcanizing drum, an endless pressure band cooperating withan arcuate portion of the drum, a plurality of rolls cooperating withthe drum to support the band and including a ten-sioning roll forplacing the band under pressure on the drum, hydraulically operatedpistons operative against the opposite ends of the tension roll in adirection tending to move them away from the drum, and means forindependently controlling the operative pressure against the pistons;the combination of an indicator cooperating with one end of thetensioning roll, and a flexible cable attached to the indicator andcooperating with the other end of the tensioning roll for indicating'onthe indicatorthe relative lateral movement of said ends under the actionof the pistons.

4. In a vulcanizing machine comprising a cylindrical vulcanizing drum,an endless pressure band of sheet steel cooperating with an arcuateportion or the drum, a plurality of rolls cooperating with the drum tosupport the band and including a tensioning roll for placing the bandunder pressure on the drum, and means for varying the axial parallelismof the tensioning roll relative to the drum and other rolls; thecombination of a single gauge positioned on one end of the tensioningroll and a connecting element attached to the gauge and connected to theother end of the tensioning roll to indicate on the gauge the parallelrelationship and the departure therefrom of the tensioning r011 relativeto the drum.

5. In a'vulcanizing machine comprising a, cylindrical vulcanizing drum,an endless pressure band cooperating with an arcuate portion of thedrum, a plurality of roll cooperating with the drum to support the bandand including a tensioning roll for placing the band under pres-sure onthe drum, hydraulically operated pistons operative against the oppositeends of the tensioning roll in a direction tending to move them awayfrom the drum, and means at one side of the machine for independentlycontrolling the operative pressure against the pistons; the combinationof a gauge cooperating with one end of the tensioning roll to partake ofits movement parallel with said direction, and a connecting elementattached to the gauge and cooperating with the other end of thetensioning roll to indicate on the gauge the relative movement of saidends of the tensioning roll under the action of the pistons.

GROSVENOR D. MIARCY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

